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| United States Patent |
5,344,582
|
|
Umemoto
, et al.
|
September 6, 1994
|
Traction fluid derived from cyclopentadiene oligomers
Abstract
A traction fluid lubricant is disclosed which contains a naphthenic
ingredient having a weight average molecular weight of 200-300 and
obtained by hydrogenating oligomers of cyclopentadiene having a ratio of
the number of norbornenic double bond to that of cyclopentenic double bond
of smaller than 0.9 but not smaller than 0.1. The naphthenic ingredient is
suitably used in conjunction with an auxiliary ingredient selected from a
polybutene having a viscosity of 5-60 cSt at 40.degree. C. and a
bicyclohexyl compound.
| Inventors:
|
Umemoto; Noboru (Kamifukuoka, JP);
Nomura; Takeshi (Tsurugashima, JP);
Kuribayashi; Toshiaki (Tsurugashima, JP);
Sato; Takehisa (Saitama, JP);
Tomizawa; Hirotaka (Tokorozawa, JP)
|
| Assignee:
|
Tonen Corporation (JP)
|
| Appl. No.:
|
921131 |
| Filed:
|
July 29, 1992 |
Foreign Application Priority Data
| Current U.S. Class: |
508/110; 252/73; 508/591; 585/10; 585/21; 585/255; 585/259; 585/317 |
| Intern'l Class: |
C10M 105/02; C10M 105/04 |
| Field of Search: |
252/9,73,11,
585/10,13,21,259,255,317
|
References Cited
U.S. Patent Documents
| 3440894 | Apr., 1969 | Hammann et al. | 252/73.
|
| 3608385 | Sep., 1971 | Duling et al. | 252/73.
|
| 3836596 | Sep., 1974 | Hayashida et al. | 585/510.
|
| 3966624 | Jun., 1976 | Duling et al. | 252/73.
|
| 4023980 | May., 1977 | Prillieux et al. | 585/13.
|
| Foreign Patent Documents |
| 0207776 | Jan., 1987 | EP.
| |
| 0402881 | Dec., 1990 | EP.
| |
| 3834622 | Apr., 1990 | DE.
| |
| 2171988 | Sep., 1973 | FR.
| |
| 1-197594 | Aug., 1989 | JP.
| |
| 1-230696 | Sep., 1989 | JP.
| |
| 1190836 | May., 1970 | GB.
| |
Other References
Patent Abstracts of Japan, vol. 15, No. 289, Jul. 1991.
Patent Abstracts of Japan, vol. 11, No. 13, Jan. 1987.
Database WPIL Week 8633, AN 86-216182, Jul. 1986.
|
Primary Examiner: Willis, Jr.; Prince
Assistant Examiner: Diamond; Alan D.
Attorney, Agent or Firm: Lorusso & Loud
Claims
What is claimed is:
1. A traction fluid comprising a naphthenic ingredient having a weight
average molecular weight of lower than 250 but not lower than 200 and
obtained by hydrogenating oligomers of cyclopentadiene having a ratio of
the number of the norbornenic double bonds to that of the cyclopentenic
double bonds in the range of between 0.3 and 0.6.
2. A traction fluid comprising a naphthenic ingredient having a weight
average molecular weight of 200-300 and containing at least 70% by weight
of hydrogenated trimers and tetramers, said naphthenic ingredient being
obtained by hydrogenating oligomers of cyclopentadiene having a ratio of
the number of norbornenic double bonds to that of cyclopentenic double
bonds of between 0.03 and 0.6, and an auxiliary ingredient selected from
the group consisting of
a polybutene in an amount of 5-70%, based on the total weight of said
polybutene and said naphthenic ingredient, said polybutene having a
viscosity of 5-60 cSt at 40.degree. C.,
a compound expressed by the general formula (I);
##STR6##
wherein R.sup.1 through R.sup.4 represent independently from each other a
hydrogen atom, a methyl group or an ethyl group, said compound of the
formula (I) being present in an amount of 5-50% based on the total weight
of said compound of the formula (I) and said napththenic ingredient; and
mixtures thereof.
3. A traction fluid as claimed in claim 1 wherein said naphthenic
ingredient has a weight average molecular weight of lower than 250 but not
lower than 200.
Description
This invention relates to a traction fluid.
Traction fluid is a term used to identify a class of lubricants that give
improved performance in traction drive. More particularly, traction fluid
is used in a device, such as a non-stage transmission device for
automobiles, in which traction drive transfers force from one rotating
rigid body to another through rolling contact. The traction fluid is
applied to such a contact portion to efficiently transmit the driving
force and to prevent direct contact between the rigid bodies. Namely, such
a traction fluid exhibits an increased viscosity upon being pressed by the
rigid bodies to efficiently transfer the drive force with minimum slip but
shows suitable fluidity immediately upon being released from the contact
portion.
One of the important characteristics of traction fluid is the coefficient
of traction. The higher the traction coefficient, the better becomes the
transfer of drive force. With a traction fluid with a high traction
coefficient, the traction drive device can be made compact. Another
desirable property of traction fluid is viscosity thereof. Too high a
viscosity causes a loss of energy for the stirring of the fluid and is
disadvantageous because the fluid fails to exhibit required
characteristics at the start of the operation in which the fluid is still
cold. When the viscosity is considerably low, a liquid film is failed to
be formed between the contact portion of the rolling members at a high
temperature, causing seizure. Resistance to heat and oxidation is also
required for traction fluids similar to ordinary lubricants.
JP-A-1-230696 proposes a traction fluid which includes a product having a
weight average molecular weight of 250 or more and obtained by
hydrogenating a polymer of dicyclopentadiene and/or
dihydrodicyclopentadiene.
JP-A-l-197594 discloses a traction fluid including, as a basestock, a
product which contains trimers to hexamers of cyclopentadiene as a major
ingredient, which has a dynamic viscosity at 40.degree. C. of 1-200 cSt
and which is obtained by hydrogenating a cyclopentene-type, condensed
hydrocarbon containing at least one polymer obtained by thermally
polymerizing cyclopentadienes such that the ratio (ND/CD) of the amount of
norbornenic double bond to the amount of cyclopentenic double bond is in
the range of 0.9-1.3.
These known traction fluids are, however, not fully satisfactory in
traction properties such as coefficient of traction and viscosity.
The present invention has been made to provide an improved traction fluid
having both a high traction coefficient and suitable viscosity. In
accordance with one aspect of the present invention, there is provided a
traction fluid comprising a naphthenic ingredient having a weight average
molecular weight of 200-300 and obtained by hydrogenating oligomers of
cyclopentadiene having a ratio of the number of the norbornenic double
bond to that of the cyclopentenic double bond of smaller than 0.9 but not
smaller than 0.1, and an auxiliary ingredient selected from the group
consisting of a polybutene having a viscosity of 5-60 cSt at 40.degree.
C., a compound expressed by the general formula (I) and mixtures thereof:
##STR1##
wherein R.sup.1 through R.sup.4 represent independently from each other a
hydrogen atom, a methyl group or an ethyl group.
In another aspect, the present invention provides a traction fluid
comprising a naphthenic ingredient having a weight average molecular
weight of lower than 250 but not lower than 200 and obtained by
hydrogenating oligomers of cyclopentadiene having a ratio of the number of
the norbornenic double bond to that of the cyclopentenic double bond of
smaller than 0.9 but not smaller than 0.1.
BRIEF DESCRIPTION OF THE DRAWING
The present invention will now be described in detail below with reference
to the accompanying drawings in which the sole FIGURE is a graph showing a
relationship between the coefficient of traction and the mixing ratio of
polybutene to naphthenic ingredient of the traction fluids according to
the present invention.
In the present invention, a naphthenic ingredient having a weight average
molecular weight of 200-300 and obtained by hydrogenating a mixture of
cyclopentadiene oligomers is used as an essential ingredient. The
oligomers have a ratio of the number of the norbornenic double bond to
that of the cyclopentenic double bond of smaller than 0.9 but not smaller
than 0.1, preferably in the range of between 0.3 and 0.6.
It is important that the naphthenic ingredient has a weight average
molecular weight of 200-300. When the average molecular weight exceeds
300, high coefficient of traction cannot be obtained. Too small a weight
average molecular weight below 200 is also undesirable because of the same
reason as above. Preferably, the naphthenic ingredient has a weight
average molecular weight of lower than 250 but not lower than 200. It is
preferred that the naphthenic ingredient contain hydrogenated trimers
and/or hydrogenated tetramers of cyclopentadiene as a major component
thereof. In particular, the total amount of the hydrogenated trimers and
tetramers in the naphthenic ingredient is preferably at least 70% by
weight, more preferably at least 75% by weight.
Illustrative of hydrogenated tetramers are as shown by the formulas
(II)-(VI):
##STR2##
The compound (II) is a product resulting from successive Dieis-Alder
reaction of cyclopentadiene, followed by hydrogenation. The compounds
(III)-(VI) are hydrogenated products of tetramers of cyclopentadiene
formed through ordinary addition reaction as well as Dieis-Alder reaction.
Hydrogenated trimers have structures similar to (II)-(VI) except that one
of the rings thereof is not present. The non-hydrogenated precursor of the
compound (VI) has a ratio of the norbornenic double bond to the
cyclopentenic double bond of 0. The naphthenic ingredient to be used in
the present invention is relatively rich in trimer and tetramers similar
to the compounds (III)-(VI) and, for this reason, the traction fluid of
the present invention is considered to exhibit high coefficient of
traction.
The above naphthenic ingredient may be produced in any known manner. For
example, cyclopentadiene-containing raw material feed is reacted at a
temperature of 160.degree.-300.degree. C. for 0.1-10 hours in the presence
or absence of a solvent in an inert gas atmosphere to obtain a product
containing cyclopentadiene oligomers. If desired, the thermal
polymerization may be further continued after the removal of unreacted raw
materials and the solvent. The reaction conditions are controlled so that
the oligomer product has one or more norbornen rings and one or more
cyclopentene rings in such a proportion that the ratio of the number of
the norbornenic double bonds to that of the cyclopentenic double bonds is
smaller than 0.9 but not smaller than 0.1. This ratio may be determined by
proton NMR analysis. The raw material feed is preferably a cyclopentadiene
fraction obtained by steam cracking of naphtha and containing at least 30%
by weight of cyclopentadiene.
The oligomer product is then subjected to a hydrogenation treatment. The
hydrogenation may be carried out by, for example, contacting the oligomer
product with a hydrogenation catalyst, such as a nickel, palladium or
platinum catalyst, at a temperature of 70.degree.-300.degree. C. under a
hydrogen pressure of 10-200 kg/cm.sup.2 for 0.5-20 hours in the presence
or absence of a solvent. The hydrogenated product which contains
hydrogenated oligomers, petroleum resins and others is then subjected to a
separation treatment to isolate the hydrogenated oligomers. The oligomers
thus obtained may be used as such for the preparation of the traction
fluid. If desired, the hydrogenated oligomer product may be distilled to
obtain a high boiling point fraction (boiling point of
150.degree.-180.degree. C. at 2 mmHg) and a low boiling point fraction
(boiling point of 110.degree.-150.degree. C. at 2 mmHg). These fractions
are blended in a suitable blending ratio to obtain the naphthenic
ingredient having a desired viscosity.
The above naphthenic ingredient is used in conjunction with an auxiliary
ingredient selected from a polybutene having a viscosity of 5-60 cSt at
40.degree. C., a compound expressed by the general formula (I) and
mixtures thereof:
##STR3##
wherein R.sup.1 through R.sup.4 represent independently from each other a
hydrogen atom, a methyl group or an ethyl group.
The term "polybutene" used herein is intended to include hydrogenated
derivatives thereof. The polybutene is preferably poly(isobutylene) having
the following formula (VII):
##STR4##
wherein n represents the degree of polymerization and is a number
providing a viscosity at 40.degree. C. of 5-60 cSt. Hydrogenated
poly(isobutylene) having the formula (VIII) is also preferably used:
##STR5##
It is important that the polybutene to be blended with the naphthenic
ingredient have a viscosity of 5-60 cSt at 40.degree. C. When the
viscosity is lower than 5 cSt, the resulting traction fluid is poor in
thermal stability and oxidation stability. On the other hand, a viscosity
higher than 60 cst causes a problem because the traction fluid cannot show
adequate viscosity.
The conjoint use of the naphthenic ingredient and the polybutene provides
the following effects. Firstly, the traction fluid exhibits suitable
viscosity of 10-80 cSt at 40.degree. C., more desirably 10-60 cSt at
40.degree. C. Secondly, the traction fluid unexpectedly shows a
coefficient of traction higher than those obtained when the naphthenic
ingredient and the polybutene are used by themselves. For reasons of
obtaining such a synergistic effect and a suitable viscosity, it is
preferred that the blending ratio of the polybutene to the naphthenic
ingredient be 5:95 to 70:30, more preferably 5:95 to 65:35.
Another auxiliary ingredient to be used together with the naphthenic
ingredient is a bicyclohexyl compound of the formula (I). Preferably, two
of the four substitutents R.sup.1 through R.sup.4 of the compound (I)
represent hydrogen. Examples of suitable bicyclohexyl compounds include
bicyclohexyl, ethylbicyclohexyl, diethylbicyclohexyl and
triethylbicyclohexyl.
The conjoint use of the naphthenic ingredient and the bicyclohexyl compound
can give an improvement in traction coefficient, viscosity and oxidation
stability. Furthermore, the bicyclohexyl compound can prevent the loss of
the traction fluid by vaporization during use. The mixing ratio of the
bicyclohexyl compound to the naphthenic ingredient is generally 5:95 to
50:50, preferably 10:90 to 50:50. If desired, the bicyclohexyl compound
may be used together with the polybutene.
It has been found that the above-described naphthenic ingredient can give
desired traction properties and viscosity without the auxiliary ingredient
so far as the weight average molecular weight thereof is lower than 250
but not lower than 200, though the use thereof in conjunction with the
auxiliary ingredient is more preferred.
The traction fluid according to the present invention can contain known
additives such as an anti-oxidant, a viscosity index improver, a metal
deactivator, an anti-wear agent, a rust preventing agent and anti-foaming
agent. Further, if desired, other conventional lubricants, such as
paraffinic mineral oils, naphthenic mineral oils and hydrocarbon oils and
oxygen-containing liquids such as esters and ethers, may be incorporated
into the traction fluid of the present invention.
The following examples will further illustrate the present invention.
EXAMPLE 1
63 Parts by weight of a naphthenic ingredient having a weight average
molecular weight of 280 and containing 84% by weight of hydrogenated
tetramers of cyclopentadiene (balance being hydrogenated trimers,
pentamers and other oligomers) was mixed with 37 parts by weight of
polyisobutylene (POLYBUTENE NAS-5H manufactured by Nihon Yushi K. K.)
having a viscosity of 11.0 cSt at 40.degree. C. to obtain a traction
fluid. The naphthenic ingredient was a product obtained by hydrogenating a
mixture of oligomers of cyclopentadiene having a ratio of the amount of
norbornenic double bond to the amount of cyclopentenic double bond of
0.59. The traction fluid was then measured for its viscosity (according to
JIS K 2283), viscosity index, thermal stability (JIS K 2540), oxidation
stability (JIS K 2514) and coefficient of traction. The coefficient of
traction was measured as follows. A Soda-type, four-roller traction tester
is employed. The test conditions involve an oil temperature of 30.degree.
C., a roller temperature of 30.degree. C., an average Hertzian pressure of
1.2 GPa, a rolling speed of 3.6 m/s and slip ratio of 3.0%. These
conditions generally give maximum value of coefficient of traction. The
thermal stability and the oxidation stability of the traction fluid were
excellent. The other results were as summarized in Table 1.
EXAMPLE 2
85 Parts by weight of a naphthenic ingredient having a weight average
molecular weight of 231 and containing 36% by weight of hydrogenated
tetramers of cyclopentadiene 60% by weight of hydrogenated trimers of
cyclopentadiene (balance being pentamers and other oligomers) was mixed
with 15 parts by weight of the above polyisobutylene to obtain a traction
fluid. The naphthenic ingredient was a product obtained by hydrogenating a
mixture of oligomers of cyclopentadiene having a ratio of the amount of
norbornenic double bond to the amount of cyclopentenic double bond of
0.30. The traction fluid was then measured for its physical properties in
the same manner as that in Example 1. The thermal stability and the
oxidation stability of the traction fluid were excellent. The other
results were as summarized in Table 1.
COMPARATIVE EXAMPLE 1-3
Traction fluids were prepared by mixing polybutenes and naphthenic
ingredients as shown in Table 1 with a blending ratio as shown in Table 1.
The thus obtained traction fluids were tested for their physical
properties in the same manner as that in Example 1. The thermal stability
and the oxidation stability of the traction fluids are found to be
excellent. The other results were as summarized in Table 1.
In Examples 1 and 2 and Comparative Examples 1-3, the polybutene/naphthenic
ingredient mixing ratio is so selected as to give a suitable viscosity of
20-25 cSt at 40.degree. C.
COMPARATIVE EXAMPLE 4
Traction fluids were prepared by mixing polybutene having a viscosity at
40.degree. C. of 5 cSt with each of the naphthenic ingredients used in
Examples 1 and 2 and Comparative Examples 1-3. The resulting traction
fluids are found to be poor in thermal stability and in oxidation
stability.
COMPARATIVE EXAMPLE 5
Traction fluids were prepared by mixing polybutene having a viscosity at
40.degree. C. of 60 cSt with each of the naphthenic ingredients used in
Examples 1 and 2 and Comparative Examples 1-3. None of the resulting
traction fluids show a desired viscosity in the range of 10-80 cSt at
40.degree. C.
COMPARATIVE EXAMPLES 3-5
Traction fluids were prepared by mixing polybutenes and naphthenic
ingredients as shown in Table 1 with a blending ratio as also shown in
Table 1. The naphthenic ingredient used in Example 4 is the same as that
used in Example 1. The naphthenic ingredient used in each of Examples 3
and 5 contained 75% by weight of hydrogenated tetramers of cyclopentadiene
(balance being hydrogenated trimers, pentamers and other oligomers) and
was a product obtained by hydrogenating a mixture of oligomers of
cyclopentadiene having a ratio of the amount of norbornenic double bond to
the amount of cyclopentenic double bond of 0.41. The thus obtained
traction fluids were tested for their physical properties in the same
manner as that in Example 1. The thermal stability and the oxidation
stability of the traction fluids are found to be excellent. The other
results were as summarized in Table 1.
TABLE 1
__________________________________________________________________________
Weight
Average
Polybutene/
Viscosity of
Molecular
Naphthenic
Physical Properties of Traction Fluid
Polybutene
Weight of
Ingredient
Viscosity
Viscosity
Example
at 40.degree. C.
Naphthenic
Mixing at 40.degree.
at 100.degree.
Viscosity
Coefficient
No. (cSt) Ingredient
Ratio C. (cSt)
C. (cSt)
Index
of Traction
__________________________________________________________________________
1 11.0 280 37:63 24.5 4.06 25.1 0.0958
2 11.0 231 15:85 23.3 4.09 50.3 0.0985
Comp. 1
11.0 340 87:13 21.0 3.98 71.9 0.0818
Comp. 2
11.0 425 90:10 20.4 3.79 51.7 0.0820
Comp. 3
21.0 195 85:15 20.2 3.77 51.5 0.0821
3 11.3 260 33:67 23.5 3.69 -31.7
0.0943
4 31.0 280 41:59 52.8 6.65 68.5 0.0927
5 31.0 260 38:62 51.0 6.16 46.4 0.0921
__________________________________________________________________________
EXAMPLE 6
A naphthenic ingredient having a weight average molecular weight of 280 and
containing 84% by weight of hydrogenated tetramers of cyclopentadiene
(balance being hydrogenated trimers, pentamers and other oligomers) was
mixed with polyisobutylene having a viscosity of 11 cSt at 40.degree. C.
with various blending ratios. The naphthenic ingredient was a product
obtained by hydrogenating a mixture of oligomers of cyclopentadiene having
a ratio of the amount of norbornenic double bond to the amount of
cyclopentenic double bond of 0.59. The coefficient of traction of each of
the thus obtained traction fluids was measured to give the results shown
in FIG. 1. The conjoint use of the naphthenic ingredient and the
polybutene gives a synergistic effect.
EXAMPLE 7
A mixture of cyclopentadiene oligomers having a ratio of the amount of
norbornenic double bond to the amount of cyclopentenic double bond of 0.43
was hydrogenated to obtain a naphthenic ingredient. The thus obtained
naphthenic ingredient was subjected to fractional distillation to obtain
Fractions A and B whose physical properties and compositions were as shown
in Table 2.
TABLE 2
______________________________________
Physical Properties
Viscosity Viscosity Composition (wt. %)
Frac- at 40.degree.
at 100.degree.
Viscosity Tetra-
tion C. (cSt) C. (cSt) Index Trimer
mer Others
______________________________________
A 10.25 2.63 82.9 96.8 3.2 none
B 255.0 11.26 -89.6 0.1 99.2 0.7
______________________________________
The Fraction A (53 parts by weight) was blended with the Fraction B (47
parts by weight) to obtain a traction fluid having a viscosity at
40.degree. C. of 23.36, a viscosity at 100.degree. C. of 4.07, a viscosity
index of 46.5, a weight average molecular weight of 238 and a coefficient
of traction of 0.1010. The thermal stability and the oxidation stability
of the traction fluid are found to be excellent.
EXAMPLE 8-12
The Fractions A and B obtained in Example 7 were blended with the blending
ratios shown in Table 3 to obtain naphthenic ingredients having physical
properties as shown in Table 3. Each of the naphthenic ingredients was
then mixed with an additive (bicyclohexyl (BCH), ethylbicyclohexyl (EBCH)
or triethylbicyclohexyl (TBCH)) as shown in Table 3 with the mixing ratio
shown in Table 3 to obtain a traction fluid whose properties are also
summarized in Table 3. In Table 3, the weight loss is measured as follows:
Sample (W.sub.0 g) is heated at 120.degree. C. and maintained at that
temperature for 5 hours. Thereafter, the weight (W1) of the sample is
measured. The weight loss is defined by the following equation:
Weight Loss (%)=(W.sub.0 -W.sub.1)/W.sub.0 .times.100
It will be apparent from the results shown Tables 1 and 3 and FIG. 1, that
the traction fluids according to the present invention exhibit a high
coefficient of traction and, at the same time, have a suitable viscosity.
TABLE 3
__________________________________________________________________________
Naphthenic Ingredient Physical Properties of
Blending Additive Traction Fluid
Ratio of
Viscosity
Weight
Amount Amount
Viscosity Weight
Fraction
at 40.degree.
Average
(parts by (parts by
at 40.degree.
Coefficient
Loss
Example
A:B C. (cSt)
M.W. weight)
Compound
weight)
C. (cSt)
of Traction
(wt. %)
__________________________________________________________________________
8 30:70
65.90
247 83 BCH 17 24.89
0.0987
46
9 30:70
65.90
247 80 EBCH 20 26.72
0.0986
45
10 0:100
255.0
268 70 BCH 30 22.84
0.1008
42
11 30:70
65.90
247 50 TBCH 50 25.59
0.0935
40
12 64:36
25.97
226 100 -- 0 25.97
0.0977
65
__________________________________________________________________________
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